System for raising and lowering large movable structures



April 12, 1960 R. R. RANSON SYSTEM FOR RAISING AND LOWERING LARGEMOVABLE STRUCTURES 6 Sheets-Sheet 1 Filed NOV. 4, 195'? LLOL5 LLILS DIFFERENTIAL SYNCQO RECEIVER April 12, 1960 R. R. RANSON 2,932,171

SYSTEM FOR RAISING AND LOWERING LARGE MOVABLE STRUCTURES Filed Nov. 4,1957 6 Sheets-Sheet 2 SLIDE BLOCK LIMIT SWITCHES L LPLSO- LPLSD' LPLS63%.5 SKEW LIMIT SWITCHES MOS DSIZSKC DSIZSKD MDSRSKE @agsil LIMITSWITCHES LqLs LGLSC-l LGLSD lrrlzzqzzzz @mm CONTACT OPEN conmcr cwsso 8afl/f/fim April 12, 1960 Filed NOV. 4, 1957 L1 L2 L3 R. R. RANSON2,932,171

SYSTEM FOR RAISING AND LOWERING LARGE MOVABLE STRUCTURES 6 Sheets-Sheet3 Mg 5a v suns BLOCK wc o 2 mm:

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E unuw w KL Z I. PC M-4 1 6 LGLSD April 12, 1960 R. R. RANSON SYSTEM FORRAISING AND LOWERING LARGE MOVABLE STRUCTURES Filed Nov. 4, 1957 6Sheets-Sheet 6 SLIDE BLOCK LIMIT SWITCHES W w WW SYSTEM FOR RAISING ANDLOWERING LARGE MOVABLE STRUCTURES Richard R. Ranson, Whitefish Bay,Wis., assignor to Cutler-Hammer, Inc., Milwaukee, Wis, a corporation ofDelaware Application November 4, 1957, Serial No. 694,343 19 Claims.(Cl. 61--2S) This invention relates to an improved system for raisingand lowering large movable structures.

While not limited thereto, particularly suitable for use with verticallymovable gates in navigation locks.

Vertically movable submersible gates are now being used at the upperpool ends of navigation locks. These gates which are often in excess of100 feet in length and 100 tons in weight move in guideways and recessesformed in the masonry side and bottom walls of the lock. Theirdimensions and weight requires use of independent hoisting systems foreach end of the gate. Differences in performance between the independenthoistmg systems, and retardation of movement of either end ofthe gatedue to the presence of foreign material in the guideways requires thatprovision be made against occurrence of skew conditions that might causesuch jamming of the gate in the guideways.

herent safety in its operation.

Another object is to provide a system of the aforementioned type whichaifords automatic skew correction if the skew is within predeterminedlimits both during normal running and during acceleration.

A further object is to provide a system of the aforementioned type whichprovides automatic stopping of the structure if such skew exceeds theaforementioned predetermined limits.

object is to provide a system of the aforementioned type whereinfollowing extreme skew stopping or shut down, automatic leveling ofthestructure will occur when tor.

Other objects and advantages of the invention will hereinafter appear.

In carrying out the invention I provide duplicate hydraulic hoistingsystems for each end of a movable struc-' ture such as a gate of anavigation lock Such systems comprise pistons connected through cablesand pulleys to the gate ends, electric motor driven fluid meter-pumphaving connection with opposite ends of the piston cylinders and havingslide block control elements which are movable in reverse directions,from a center or neutral zone to afford various metering and pumpingrates for the meter-pump to afford raising andlowering of the respectiveends of the gate. These slide block control elements are driven inreverse directions by reversible elec tric motors. A controlsystem isprovided for the lat ter motors and permits selection of raisin'gandlowering operation and initiation of leveling following stopping becauseof an extreme skew condition. The control incorporates means continuallycomparing the difference-in level between the ends of the'gates duringraisingand lowering and if skewtherebetween' exceeds a given the presentinvention is such operationis initiated by the operabe assumed to' restat'its lowe'r 2,932,171 Patented Apr. 12, 1960 amount initiatesreadjustment of the slide block control element of the meter-pumpassociated with the leading end of the gate until the gate ends areagain substantially in level. If such correction is ineffective and theskew increases beyond a predetermined greater amount the latter meansinitiates immediate shut down of both hydraulic systems and setting ofvalves in the hydraulic lines to stop and hold the gate in the positionthen attained. Following such shut down automatic leveling of gate endscan be effected by manual initiation of such operation. 7 v Theaccompanying drawings illustrate a preferred embodiment of the inventionwhich will now be described in detail, it being understood that theembodiment illus trated is susceptible ofmodification in respect ofdetails without departing from the scope of the appended claims. In thedrawings: Figure l is a schematic showing of a vertical lift gate from anavigation lock together with hydraulic hoists for each end of the'gateand certain of the control means therefor;

Fig. 2 is a chart depicting the operation of certain limit switchesshown in Fig. 1;

Fig. 3 is a chart depicting the operation of certain other limitswitches shown in Fig. 1;

Fig. 4 is a chart depicting the operation of still other limit switchesshown in Fig. l; I Figs. 5a to Sc diagrammatically depict the electricalhook-up of an electrical control system for the appara tus shown in Fig.l;

Fig. 6 depicts a modification of a portion of the sys tem shown in Fig.1; and

Fig. 7 is a chart depicting the operation of additional limit switchesused in the modified system of Fig. 6.

Fig. 1 shows a vertical lift gate 7, such as is used in the upper poolend of a navigation lock. It may be as;- sumed that gate 7 moves in,and, portions of its left and right-hand sides are overlapped byguideways (not shown) formed in the side walls of the lock. assumed thatin its lowermost or openf position that the lower portion of the gate isdisposed in a recess or well (not shown) formed in the bottom wall ofthe lock, which communicates with the aforementioned guideways.

A hydraulic piston '8, which is reversely movable with in a cylinder 9,has a connecting rod '10 on the upp'e'r end of which is rotatablymounted a plurality of pulleys, depicted by pulley 11. A plurality ofcables, depicted by cable 12, are affixed at one end to an abutment 13,pass around the pulley 11, over idler pulleys 14 and 15 and are securedat their other ends to gate 7 adjacent the upper left-hand end thereof.Similarly, a piston 16, which moves in a cylinder 17 has a connectingrod 18 on which is mounted aplurality of pulleys 19. Cables 20 which areaflixed atone end to abutment 21 pass around the pulleys 19, aroundidler pulleys 22 and 23 and are attached at their other ends to gate 7against the upper right-hand end thereof. It will be seen that whenfluid is pumped into cylinders 9 and 1 7 above. pistons 8 and 16 to movethelatter downwardly, gate-7 will be caused to move upwardly, and thatwhen fluid is exhausted from cylinders 9 and 17 above, pistons 8 and 16,the gate will move downwardly under its own weight.

When the gate is in its upper or closed position holding latches 24 and25 are inserted by motive means (not shown) into recesses 7a" and 7b ofthe gate to relieve the weight of the gate from the cables and hydraulicsystern. When lowering operation of the gate is initiated, as willhereinafter be fully described, latches Hand 25 are withdrawn before thegate commences to lower. When the gate is'in its lower-or open position'itmay Also it may be end on bumpers (not- 2,074,068, issued March 16,1937. These pumps, have -slide block control elements 26a and27a,respectively.

It is a characteristic of such pumps to have a center slide blockposition of indeterminate width wherein the pump functions neither as apump nor as a metering device. As will be hereinafter more fullyexplained,

-in order to avoid control complications I arbitrarily pro- :vide aneutral zone of slide block positioning of a .width sufi'icient toinsure that the pump will definitely function as a pump when it is movedbeyond the limit of such neutral zone in one direction and willdefinitely function as a metering device when moved beyond the oppositelimit of such zone. If moved upwardly as :depicted in Fig. 1, they. may.be assumed to move into the ?pumping region whence they may be assumedto cause meter-pumps 26 and 27 to pump fluid upwardly into the conduits28 and 29, which communicate interiorally at the upper ends ofcylinders, and within limits the farther the slide blocks are moved intothe pumping regions, the greater will be the displacement or rate offluid pumping. Conversely, if the slide blocks are moved out of theirneutral zones downwardly as depicted in Fig. 1, they may be assumed tocause meter pumps 26 and 27 to meter fluid out of conduits 28 and 29,into the conduits 30 and 31 which communicate interiorally at the lowerends of cylinders 9 and 17. Within limits the farther the slide blocksare moved into their metering regions the greater .will be the meteringrate or displacement.

Valves LBV and RBV are interposed in conduits 28 and 29, respectively,and are provided with solenoid operating windings LBV1 and RBV1 which,when energized afiord opening of brake valves LBV and RBV to permitfluid flow into or out of the upper ends of cylinders 9 and 17. Whenwindings LBV1 and RBV1 are deenergized flow of fluid in the respectivehydraulic system is stopped and the positions of the pistons in thecylinders maintained to hold the gate ends in a position correspondingthereto.

Meter pumps 26 and 27 are driven by A.C. electric motors 34 and 35,respectively, and the latter motors are provided with electromagneticbrakes 34a and 35a. Brakes 34a and 35a insure against operation of pumps26 and 27 as hydraulic motors in the event of simultaneous power failureto motors 34 and 35 and brake valves LBV and RBV. Slide block 26a ismovable in reverse directions as aforedescribed by a reversible A.C.electric motor 36 having an electromagnetic brake 36a, and slide block27a'is similarly movable by an A.C. electric motor 37 having anelectromagnetic brake 37a.

Motor 36 in driving slide block 26a concurrently drives a traveling nutfollower 26b in a corresponding direction from a neutral zone tosuccessively operate limit switches LPLSD and LPLSF as the slide blockmoves into its pumping region. As the slide block moves into itsmetering region limit switches LPLSC and LPLSA are operated by thefollower 26b. Motor 37 similarly drives a traveling nut follower 27b incorresponding direction with slide block 27a to successively operatelimit switches RPLSD and RPLSF as slide block 26b is moved into itspumping region, and to successively operate limit switches RPLSC andRPLSA as the latter slide block is moved into its metering region. Theaforementioned limit switches are reset in reverse order as theassociated slide blocks are moved back into their neutral zones fromtheir pumping and metering regions. Fig. 2 depicts the sequence andopen-closed direction of the various contacts of limit switches LPLSA,LPLSC, LPLSD and LPLSF. This will also hold true for limit switchesRPLSA, RPLSC, RPLSD-and 'RPLSF. When latch 24 V r -r...

is fully withdrawn as depicted in Fig. 1 it trips a limit switch LLOLSand when fully inserted it trips a limit switch LLILS. Similarly, latch25 when fully withdrawn trips a limit switch RLOLS and when fullyinserted trips a limit switch RLILS.

A member 38 attached at one end to connecting rod 10 is connected at itsother end to a roller chain 39 which runs on an idler sprocket wheel 40and a sprocket wheel 41 which has a shaft 42 afiixed thereto. Shaft 42rotates to operate gate position limit switches LGLS-A, LGLS-B, LGLS-Cand LGLS-D to operate them in accordance with the elevation of the leftend of the gate which will hereinafter be more fully described and alsodrives a synchro transmitter 43. Similarly, a member 44 which isattached to one end to connecting rod 18 is connected at its other endto a roller chain 45 which runs on an idler sprocket wheel 46 and asprocket wheel 4-7 which has a shaft 48 affixed thereto. Shaft 48similarly operates gate position limit switches RGLS-A, RGLS-B, RGLS-Cand RGLS-D in accordance with the elevation of the right end of thegate, and also drives a synchro transmitter 49. Fig. 4 depicts thesequence of operation and open-closed directions for the contact limitswitches LGLS-A, LGLS-B, LGLS-C and LGLS-D and it may be assumed thatthe same will hold for the contact limit switches RGLS-A, RGLS-B, RGLS-Cand RGLS-D.

Synchro' transmitter 43 is electrically connected by a cable 50 to adifferential synchro receiver 51, and synchro transmitter 49 iselectrically connected by a cable 52 to receiver 51. Receiver 51 has anoutput shaft 53 which rotates to various angular positions in eitherdirection in accordance with (a) the difference in amount of angularrotation between shafts 42 and 48, and (b) whichever of the lattershafts has the greater angular rotation. In accordance with thedirection and degree of its rotation, shaft 53, by means of five camsfixed thereto operates five skew limit switches MDSRSKA to MDSRSKE,inclusive. Fig. 3 depicts the open-closed operating conditions for eachof the limit switches MDSRSKA to MDSRSKE. As will hereinafter beapparent, these latter switches are the means by which operation of thehydraulic hoisting and lowering systems associated with the left andright-hand ends of the gate are coordinated. Except for suchcoordination, and certain to be described control function initiatingswitches, the left and righthand hoisting and lowering systems and thecontrol therefor essentially operate independently.

Cylinders 9 and 17 have associated therewith pressure switches LPS andRPS, respectively, which function in the control system now to bedescribed.

Figs. 5a to Sc depict the electrical hook-up of the motors, brakes,valves and limit switches, etc., described in connection with thehydraulic hoisting and lowering mechanism aforedescribed in connectionwith the lefthand end of gate 7, together with others to be describedrelays, contactors and control function initiating sw tches. Thediagrams of Figs. 5a to 50 should be considered as constituting a singlediagram with each succeeding diagram connected to the bottom of thepreceding diagram, and with the individual portions of the controlsupply buses 61 and 62 connected continuously. It is to be understoodthat, except for the control function initiating switches and limitswitches MDSRSKA to MDSRSKE, the hydraulic hoisting and lowering controlsystem associated with the right-hand end of the gate would be aduplicate of that depicted in Figs. 5a to Sc, and for the sake ofsimplicity its description beyond that heretofore made will be dispensedwith. Thus all further description of operation will be in terms of theleft end of the gate, but the various modes of operation will also holdtrue for the right end.

The relays, contactors and switches associated solely with the left endsystem are prefixed by the letter L" and those of a master character byM." The following symbol designations hereinafter used in connectionwith Now considering Fig. a, it shows a polyphase AC. power supplycomprising supply lines L1, L2 and L3. The supply terminals of pumpmotor 34 are connectable to supply lines L1, L2 and L3 by closure ofcontacts LPCM1, 2 and 3 of contactor LPCM. The electromagnetic releasewinding of brake 34a is also concurrently energized to permit motor 34to drive meter-pump 26 wherein supply connections are completed to suchmotor.- The supply terminals of slide block motor 36 are connectable tosupply lines L1, L2 and L3 for operation in one direction upon closureof contacts LPCO-Z, 3 and 4 of contactor LPCO and such supply terminalsare connectable to the same supply lines in a different manner tooperate the motor in reverse'direction upon closure of contacts LPCC-2,3 and 4 of contactor LPCC. The brake release winding of brake 36a isenergized whenever power connections are completed to motor 36, anddeenergized to stop motor 36 whenever the power connections areinterrupted to the motor.

A transformer 63 has its primary winding 63a connected across supplylines L1 and L2 and has the end terminals of its secondary winding 63bconnected to the buses 61 and 62, respectively. The input terminals ofsynchro transmitters 43 and 49 are connected across the end terminals ofwinding 63b. The aforementioned cable 50 between transmitter 43 anddifferential receiver 51 comprises three electrical conductors as doesthe cable 52.

The control system of Figs. 1 and 5a to Sc, afiords (a) Normal ClosingOperation, (b) Normal Opening Operation, (0) Automatic Skew Correction,(d) EX-. treme Skew Shut Down, and (e) Manually Initiated AutomaticLeveling from Extreme Skew Shut Down Condition. A complete descriptionof the positions of the system shown in Figs. 5a to will be made inconnection with detailed descriptions of the foregoing types ofoperation which are set forth hereinafter under subheadings bearing theforegoing operation designations.

The condition of the hoisting system depicted in Fig. 1 is thatobtaining when the gate is in its lower or open position resting on thebumpers, and the condition of the electrical control system depicted inFigs. 5a to 5c is that obtaining with power supply lines L1, L2 and L3deenergized. p

If for any reason either of the slide block control elements is not inits neutral zone, it will be driven back into such zone, and both mustbe in their neutral zones before drive of the fluid pumps and theremainder of the control vsystem can function. Assume the slide blockcontrol element 26b is outside of its neutral zone n he ehsi ftsa m- Ths, on a t LBLSDB of S ide,

b ck lim s i ch PLSD l be os to c m e e a ener izin .c u in e a L R e sL P-D of relay LPCRPD thereupon close to complete an eper-1 gizingcircuit for contactor LPCO from line 61 through the then closed contactsMCRHL1-2 LCRN-4, LCRPD-IS and LPCC-l and contactor LPCO to line 62.

Brake 36a will then be released and motor 36 energized to drive slideblock element 261; back into the neutral zone and will continue untilcontacts LPLSD-3 re-open to deenergize relay LCRD3. If slide blockelement 26b is out of the neutral zone, but in the opening direction,contacts LPLSC-l of limit switch LPLSC will be closed to energize relayLCRPC resulting in closure of contact LCRPC-S of the latter.Consequently an ener giz ing circuit for contactor LPCC will becompleted from line 61 through the then closed contacts MCRHLl- -Z,LCRN-4, LCRPC-3 and LPCO-l and contactor LPCC to line 62. Motor 36 willthen be energized to drive slide block 2612 in the closing directionback into its neutra 7 zone whereupon limit switch contacts LPLSC-l opento deenergize relay LCRPC.

Normal closing operation Upon operation of a master start switch, driveof the fluid pumps is started, and then, following operation of a masterclosing-opening switch to closing position, the slide block drivingmotors are started and drive the slide block control elements out oftheir neutral zones in a direction affording operation of the meter-pumpat increasing rate or displacement. The brake valves in the conduitsleading from the meter-pump to the upper ends of the cylinders are thenopened and fluid pumped into thecylinders. The pistons are therebyaccelerated downs wardly in the cylinders and thereby move gate 7upwardly at an increasing rate. When the slide blocks of the meterpumpsreach a givenposition in their pumping region, movement thereof isstopped and fluid is then pumped into the cylinders at a high rate toraise gate at a corresponding high speed. When the gate reaches acertain position in its upward travel the slide block control elementsof the meter-pumps are driven in the opposite direction toward theirneutra zones so the displacement or rate of the meter-pump outputs arereduced, and rate of movement of the pistons and gate 7 iscorrespondingly reduced to a predetermined slow or creeping speed.

If the gate has slowed down to creeping speed when it reaches its uppernormal position the holding latches are inserted. However, in the eventthe gate has not slowed down to creeping speed when it reaches thatposition all operation of the control system will immediately stop.

When the insertion of, the holding latches is completed, the slide blockcontrol elements of the meter-pumps are; driven back through theirneutral zones and then into. their metering regions wherein themeter-pumps meter fluid out of the cylinders at a rate causing the gateto move downwardly at creeping speed until the gate comes, to rest onthe aforementioned holding latches. Finally, the slide block controlelements of the meter-pumps are driven back toward their neutral zonesand when they reach positions in the neutral zones are stopped and thebrake valves closed. Thus the gate will then be in closed, positionresting on holding latches, and the control system readied for operationto open the gate. A detailed description of operation of the controlsystem to afford the aforedescribed operation will now bemade.

Closure of a start switch 65 completes an energizing, circuit for pumpmotor contactor LPCM through closed, stop switch 64, slide block limitswitches contact LPLSC-4 and LPLSD-l, which will be closed when theslide block control elements are in their neutral zones and contactsMCRl -l. Contacts LPCM-4 close to maintain contactor LPCM around switch65 and limit switch contacts LPLSC-4 and LPLSD-l. Contacts LPCM-1, 2 and3 close to complete energizing connections, from lines; L1, L2 and L t m3 d e ra r lease ndins 7 34a to aflord drive of meter-pump 26. ContactsMCRI-l are normally open but'relay MCRl will then be energized to closethemthrough closed contacts LCRSD2-3 and closed skew limit switchMCRSKE-l. Contacts LCRSD2-3 are normally open contacts but are closed byvirtue of energiza'tion of relay LCRSDZ through then closed gateposition limit switch LGLSB and contact LGLSB-l and slide block limitswitch contacts LPLSC-3 and LPLSD-2. V

The aforementioned closure of start switch 65 also completes anenergizing circuit for a timing reiay LTR which is connected in parallelwith contactor LPCM. Upon energization relay LTR closes with time delayinsuring that the portion of the control system having to do withadmission of fluid into and out of the cylinders 9 and 17 cannot operateuntil the pump driving motors 34 and 35 have come up to full speed.

To initiate gate closing operation a three-position closing-openingselector switch MQCS is closed to its close contact to complete anenergizing circuit for relay MCRC. The latter is energized and closescontacts MCRC-l to complete an energizing circuit for relay LCRSCthrough closed, contacts LCRO2-2. Relay is maintained around contactMCRC-l by closure of its contacts LCRSC-1.

Closure of contacts MCRC-Z results in completion of an energizingcircuit through the then closed contacts MLR-2 for closing coil MLR-C ofa latched relay MLR. Contacts MLR-7 of the latter relay then close tocomplete an energizing circuit for relay MLRA. Thus an energizingcircuit will be completed for relay LCRC through the then closedcontacts MCRC-Z and MLRA-l. Thereupon contacts LCRC-2 close to completean energizing circuit for contactor LPCC through the then closedcontacts LCRSKC-l, LCRPD-l and the then closed interlock contactsLPCO-I.

Contactor LPCC then picks up and closes its contacts LPCC-4, 3 and 4 toenergize motor 36 to drive its associated slide block control element26a of meter-pump 26 out of its neutral position depicted in Fig. 1upwardly which may be assumed to afford pumping of fluid into conduit29. As the slide block continues to move traveling nut 26b operateslimit switch LPLSD.

' Closure of contacts LCRSC-2 by the aforementioned pickup of relayLCRSC results in energization of relay LCRN through then closed contactsLCRPC-4 and LCRPD-4. Pickup of relay LCRN results in closure of contactsLCRN-1 which maintains the relay around contacts LCRPC-4 and LCRPD-4.The aforementioned operation of limit switch LPLSD results in closure ofits contacts LPLSD-4 and an energizing circuit is thereby completed forrelay LCRBV through limit switch contacts LPLSD-4 and contacts LCRN-3 ofrelay LCRN. Contacts LCRBV-Z and LCRBV-3 close to complete anenergization for operating coil LBVl of brake valve LBV in conduit 28.-

Opening of valve LBVl permits meter-pump 26 to pump fluid into the upperend of cylinder 9 and as slide block 26a is then being moved towardextreme position in the pumping region, the rate of fluid flowincreases. Consequently piston 8 is caused to accelerate downwardly incylinder 9 to cause corresponding acceleration of gate in the upward orclosing direction.

The aforementioned energization of relay LCRC resulted in closure ofcontact LCRC-3 thereof and closure of the latter results in completionof an energizing circuit for relay LCRHS through the then closed limitswitch contact LGLSC-l and interlock contacts MCRMS-3 of relay MCRMS.Energization of the latter results in closure of contacts LCRHS-3 andthe latter contacts together with the then closed limit switch contactsLPLSF-l provides a maintaining circuit around contacts LCRPD-l for relayLPCC. The aforementioned operation of limit switch LPLSD results inclosure of contacts LPLSD-3 to complete an energizing circuit for relayLCRPD so that its contacts LCRPD-l' open at that time.

-' The accelerated movement of piston 8 and magma continues until thetraveling nut 26b trips limit switch LPLSF to open contacts LPLSF-l andclose contacts LPLSF-Z thereof. Opening of contacts LPLSF-l results indeenergization of contactor LPCC to deenergize slide block drive motor36 and brake release winding 36a. Movement of slide block 26a is thenstopped at an extreme position in the pumping direction, and meterpump26 then pumps fluid into cylinder 9 at a fixed displacement and piston Sand gate 7 then move at a uniform rate. LSLSA closes, LGLSB-l opens andLCRSDZ drops out.

Gate 7 is raised at high speed and at near fully raised position, limitswitch contacts LGLSC-2 close. Closure of the latter contacts completethe energizing circuit for relay LCRSD-l through the then closedcontacts LCRSDZ-Z. Closure of contacts LCRPD-3 of previously energizedrelay LCRPD and closure of contacts LCRSDZ-Z of relay LCRSDZ completesan energizing circuit for relay LCRSDl through the then closed limitswitch contacts LGLSC-Z. Simultaneously LGLSC-l opens to drop out relayLCRHS.

Energization of relay LCRSDI results in closure of its contact LCRSDl-J.completes an energizing circuit for contactor LPCO through the thenclosed contacts MCRI-IL1-2, contacts LCRSDl-l and the previously closedcontacts LCRPD-3 and closed interlock contact LPCC-4. Contacts LPCO-2, 3and 4 close to energize brake release winding 36a and motor 36 to afforddrive of slide block 26a back toward its neutral zone. In so doing theoutput of meter-pump 26 is decreased and the rate of movement of pistonS and gate 7 thereby reducedv Ultimately the traveling nut follower 26are-operates limit switch LPLSF and LPLSD and contacts LPLSF-l, LPLSD-2reclose. Closure of the latter contacts results in completion of anenergizing circuit for relay LCRSD2 through the then closed-limit switchcontacts LGLSC-2. Contacts LCRSD2-1 close to provide a maintainingcircuit for relay LCRSDZ around contacts LPLSD-2 and LPLSC-3. ContactsLCRSDZ-Z open to deenergize re lay LCRSDI. v

Deenergization of relay LCRSDI results in opening of its contactsLCRSDLI to deenergize contactor LPCO to momentarily deenergize the brakerelease winding 36a and motor 36. Interlock contacts LPCO-l recloses,and as a result, the energizing circuit is again completed fromcontactor LPCC to reenergize brake release winding 36a and motor 36 todrive slide block 26a out of the neutral zone in the pumping region.Displacement of the pumping of meter-pump 26 is thereby increased andcontinues to increase until the traveling nut slide block follower nut26b operates limit switch LPLSD. Contacts LPLSD-3 then close to againenergize relay LCRPD. Opening of contacts LCRPD-I of the latter thenresults in deenergization of contactor LPCC.

With contactor LPCC again deenergized the brake release winding 36a andmotor 36 are deenergized to stop movement of slide block 26. As a resultmeter-pump will then pump fluid at some low fixed displacement intocylinder 9, and piston 8 and gate 7 will then move upwardly at acorresponding slow creeping speed.

As the gate moves just past its upper normal or latched position, limitswitch LGLSD opens. If contacts LCRSD2-3 are not closed (signifying thatslow down operation of the slide block has not been completed), theopening of limit switch LGLSD will cause deenergization of relay MCRI.It will be'seen that opening of contacts MCRi-l results indeenergization of contactor LPCM and timing relay LTR to stop themetering pump drive motor and close the brake valve. Thus movement ofthe gate will be stopped. However, if when such check point is reachedand contacts LCRSD2-3 have closed (signifying completion of slow downoperation of the slide block),-relay MCRl will 9 be maintained energizedaround the then open limit switch LGLSD by contacts LCRSD2-3 and thegate will continue upwardly at creeping speed.

At this point it may be assumed that holding latches are moved intointerfening relation with gate 7 by any preferred means (not shown) andthat following'completion of movement of the latches a limit switchLLlLS2 re-closes to complete an energizing circuit for relay LCRLI.'Contacts LCRLI-2 of the latter thus close to complete an energizingcircuit for relay LCROl through the then closed contacts LCRSC-S, LPSIand MLRA-2. Opening coil MLR-P of latched relay MLR, due to contactsMLR-1 then being closed, is also energized in parallel with relay LCROIto trip or release latch relay MLR.

As a result of energization of relay LCROl contacts LCROl-S close tocomplete an energizing circuit for relay LCRO2. Contacts LCROZ-Z of thelatter then open to deenergize relay LCRSC. The aforementionedenergization of relay LCROI results in closure of its contacts LCRO1-3to complete an energizing circuit for contactor LPCO through the thenclosed contacts LCRSKO-l,

LCRPC-l and interlock contacts LPCC-1. Consequent- 1 1y, brake releasewinding 36a and motor 36 are again 4 energized to eifect drive of theslide block 26a back into and through its neutral zone a certain amountin the metering range. As slide block moves into the metering rangefluid is caused to flow back out of cylinder 9 to cause piston 8 to moveupwardly and gate 7 to move downwardly at creeping speed.

However, such downward movement of gate 7 is slight before the travelingnut 26b operates limit switch LPLSC-l to close its contact LPLSC-l.Closure of the latter contacts results in completion of an energizingcircuit for relay LCRPC. As a result contacts LCRPC-l open tointerruptthe energizing circuit for contactor LPCO and thus slide block26a is stopped in the position then attained. At this point gate 7 isjust slightly above the inserted latches and moving downwardly atcreeping speed and then ultimately comes to rest on the latches.

When gate 7 comes to rest on the latches pressure of "the fluid incylinder 9 decreases as the latter is metered out above piston 8.Consequently, pressure switch LPS responds to open its contacts LPSl.Opening of contacts LPSl results in deenergization of relay LCROI whenit opens its contacts LCRO1-5 to effect deenergization of relay LCRO2.Contacts LCRO1-2 also open to deenergize relay LCRN. Contacts LCRN-3thereupon open to deenergize relay LCRBV. Opening of contacts LCRBV-2and 3 of the latter results in deenergization of operating coil LBVI ofbrake valve LBV to close the latter to stop flow of fluid in conduit 28.

Deenergization of relay LCRN also results in reclosure of its contactsLCRN-4 and thus completes an energizing circuit for contactor LPCCthrough the then closed contacts MCRHLl-Z, LCRPC-3 and interlockcontacts LPCO-l. Consequently slide block 26a is then driven back intoits neutral zone. During such movement the traveling nut follower 26areoperates limit switch LPLSC to open its contact LPLSC-l which resultsin deenergization of relay LCRPC. Contacts LCRPC-3 thereupon open todeenergize contactor LPCC when slide block 26a has reached some positionwithin its neutral zone.

It can be assumed that the right-hand hoisting system will completenormal closing operation at approximately the same time, the gate 7 willthen rest level on the holding latches.

Normal opening operation rate. [The brake valves are then opened andfluid is pumped into the upper end of the cylinders to raise the gate atslow or creeping speed. The holding latches are Assuming that fluidmeter pumps are being driven,

operation of the master opening-closing switch to opening position willresult in energization of the slide-block driving motors to drive theslide blocks out o'ftheir neutral zones in .thedirection .alfordingpumping at-aslow then withdrawn and when they reach withdrawn position,the control system functions to reverse the direction of drive of theslide blocks back through their neutral" zones on into their meteringregions. The upward movement of the gate is momentarily halted, and thenmoves downwardly under its own weight at an increasing rate as the slideblocks movefarther into their metering region. The slide blocks continueto move into their metering region until predetermined positions arereached wherein they are stopped and metering of fluid from the upper tothe lower cylinder chambers then continues at a corresponding fixed rateor displacement to afford lowering of the gate at high speed. When thegate is lowered to within a given distance of its bumpers, the slideblock of the meter-pumps are driven back toward the neutral zone topositions alfording slow down of fluid metering and hence the rate ofgate lowering is reduced to creeping speed. As the gate passes a secondposition below the aforementioned predetermined position and the gatehas not slowed down to creeping speed, it will automatically be stoppedat that position. However, if it has slowed down to creeping speed whenit reaches the second position it continues on down until it rests onthe bumpers. When the weight of the gate is relieved from the cables,the brake valves close and the slide blocks then return to their neutralzones. A detailed description of operation of the control system toafford the aforedescribed operation will now be made.

To initiate gate opening operations the three-position selector switchMOCS is closed to its open contact to complete an enengizing circuit forrelay MCROI through the then closed contactsLCRSC-6 and MCRC- l.Contacts MCRO2.-3 thereupon close to energize relay LCRSO through thethen closed contacts MCRC1-3 and LCRO2- 1. Contacts LCRSO-l then closeto maintain relay LCRSO around contacts MCRO23 and contacts LCRSO-3close to complete an energizing circuit for closing coil MLR-C oflatched relay MLR through the then closed contacts LLOLS-1 and MLR-2.Latched relay MLR then operates and contacts MLR-7 close to complete anenergizing circuit for relay MLRA.

Contacts -MLRA-1 close to complete an energizing circuit for relay LCRCthrough the then closed contacts LCRSO 3 and limit switch contactsLLOLS-l and contacts MLRA-l. As a result contacts LCRC-2 close tocomplete an energizing circuit for contactor LPCC through the thenclosed contacts LCRSKC-l, LCRPD-l and interlock contacts LPCO-l. Brake36a is thereby released and motor 36 drives slide block 26a out of itsneutral zone into the pumping direction. Closure of contacts LCRSO-2results from the last mentioned energization of relay LCRSO and suchclosure completes an energizing circuit for relay LCRN through the thenclosed contacts LCRPC-d; and LCRPD-4. Closure of contacts LCRN-1maintains relay LCRN. As the slide block moves into its pumping regionit operates limit switch LPLSD to close its contacts LPLSD-4 which thenresults in completion of an energizing circuit for relay LCRBV throughthe then closed contacts LCRN-3. Re- My LCRBV is maintained aroundcontacts LPLSD-4 and LPLSC-Z by closure of its contacts LCRBV-1. Closureof contacts LCRBV-2 and 3 results in energization of coil LEVI of brakevalve-LEV, whereupon fluid is then pumped into the upper chamber ofthe'cylinder, to raise the gate ofi of its holding latches.

As the slide block 26a'moves into its pumping region it operates limitswitch LPLSD to close its contacts LPLSD-3 to complete an energizingcircuit for relay LCRPD. Contacts LCRPD-l thereupon open to demergizecontactor LPCC which results in deener-gization of motor 36 and settingof the brake 36a to stop slide block 26a in a position afiording pumpinginto the cylinder at assarvr 11 a'displace'ment or rate providingraising of'the' gate at creeping speed.

As the gate is raised off its holding latches the same may be assumed tobe withdrawn, and upon initiation of their withdrawal limit switch LILSis reset to reopen its contacts LILS-1 and consequently, relay LCRLIbecomes deenergized. When the latchesreach fully withdrawn positionslimit switch LLOLS is tripped to open its contacts LLOLS-l to deenergizerelay LCRC and to close its contacts LLOLS-Z to complete an energizingcircuit for relay LCRLO.

Energization of relay LCRLO results in closure of its contacts LCRLO-4to complete an energizing circuit for opening coil MLR- of latched relayMLR through the then closed contacts LCRSO-S, LPSl and MLR-1. Relay MLRoperates and opening of its then closed contacts MLR-1 deenergizes coilMLR-0. Contacts MLR-7 also open to deenergize relay MLRA and as a resultcontacts MLRA-2 close to energize relay LCROl. Contacts LCROi-S thenclose to complete an energizing circuit for relay LCRO2.

Energization of relay LCROl results in closure of its contacts LCRO1-3to complete an energizing circuit for contactor LPCO through the thenclosed contacts LCRSKO-l, LCRPC-l and interlock contacts LPCC-1. Theaforementioned energization of relay LCROI and closing of contactsLCRO1-4 resulted in completion of an energizing circuit for relay LCRHSthrough the then closed contacts LCRLI-4 and LGLSB-2, and thus contactsLCRHS-1 provide a maintaining circuit, in conjunction with the thenclosed contacts LPLSA-2 of limit switch LPLSA, for contactor LPCO.Contacts LPCO-Z, 3 and 4 close to energize motor 36 to drive it in thedirection to move slide block 26a through its neutral zone and beyondinto the metering direction. Consequently, the gates upward movement isstopped and then begins to move downwardly as the slide block moves intoits metering region. As the slide block moves farther into its meteringregion the rate of fluid metering increases and the gate acceleratesdownwardly.

Before slide block 26a moves into the "neutra zone from its pumpingregion limit switch LPLSD operates and contacts LPLSD-3 open todeenergize relay LCRPD, and as the slide block moves out of the neutralzone into the metering region limit switch LPLSC operates and closure ofits contacts LPLSC-1 completes an energizing circuit for relay LCRPC.The slide block continues to move father into the metering region andthe rate of movement of gate downwardly increases until limit switchLPLSA is operated to open its contacts LPLSA-2 which results indeenergization of contactor LPCO and stopping of movement of the slideblock in a given position in its metering region. The gate thereaftercontinues to move downwardly at a uniform high speed.

As the gate approaches the bumpers limit switch LGLSB is operated andclosure of its contacts LGLSB-1 completes an energizing circuit forrelay LCRSDI through the then closed contacts LCRSD2-2 of relay LCRSDZ.Contacts LCRSDl-l then close to complete an energizing circuit forcontactor LPCC through the then closed contacts MCRHL1-2, LCRPC-3 andLPCO-l. Thus the slide blocks are driven back toward the neutral zone toreduce the metering rate of the meter-pump and hence the rate oflowering of the gate. As the slide blocks move back toward the neutralzone limit switch LPLSA is reset to reclose its contacts LPLSA-2 andjust before it reaches its neutral z'one limit switch LPLSC is reset toreopen its contacts LPLSC-1 to deenergize relay LCRPC. Then contactsLCRPC-3 reopen and deenergize contactor LPCC and stop the slide blocksmomentarily in the neutral zone.

The last mentioned reset of limit switch LPLSC also results in closureof its contacts LPLSC-3 to complete an energizing circuit through theirclosed limit switch contacts LGLSB-1 and contacts LPLSD-2 for relayLCRSD2.- Closure of contacts LCRSDZ-l' maintains relay LCRSD2 aroundcontacts LPLSC3 and LPLSD-2. Contacts LCRSDZ-Z open to deenergize relayLCRSDl. The aforementioned reset of limit switch LGLSB also reopened itscontacts LGLSB-2 to deenergize relay LCRHS to open its contacts LCRHS-2and close its contact LCRHS-5.

The last mentioned deenergization of contactor LPCC results in reclosureof its contacts LPCC-1 to complete an energizing circuit through closedcontacts LCROl-3, LCRSKO-l and LCRPC-l for contactor LPCO. The slideblock moves back out of the neutral zone into the metering region andlimit switch LPLSC is tripped. Contacts LPLSC-1 thereupon close tocomplete an energizing circuit for relay LCRPC. Contacts LCRPC-l of thelatter relay then open to deenergize contactor LPCO to the slide blockin a position in the metering region afiording creeping speed loweringof the gate.

With the meter-pump metering rate reduced, the gate then slows down toapproach the bumpers at creeping speed. As it continues to lower a checkpoint is reached when limit switch LGLSA is opened. If contacts LCRSDZ-Sare not closed (signifying that slowdown operation of the slide blocklast described has not been completed), the opening of limit switchLGLSA will cause deenergization of relay MCRI. It will be seen thatopening of contacts MCRl-l will result in deenergization of contactorLPCM and timing relay LTR to stop the metering pump drive motor andclose the brake valve. On such occurrence lowering of the gate will bestopped. However, if when such chec point is reached and contactsLCRSD2-3 have closed (signifying completion of slow down operation ofthe slide block), energization of relay MCRI will be maintained bycontacts LCRSD2-3 around the then open limit switch LGLSA and the gatewill continue downwardly toward the bumpers.

When the bottom of the left side of the gate comes to rest on thebumpers the weight is relieved from the cables and pistons andconsequently, pressure switch contacts LPS-l open to deenergize relayLCROl. From here on the reclosing of the brake valve and drive of theslide block 26a of meter pump 26 back to its neutra zone will be exactlythe same as that described in detail in connection with completion ofNormal Closing Operation. It may be assumed that the right side hoistingsystem will complete its Normal Opening operation at approximately thesame time and thus the entire gate will rest on the bumpers insubstantially a level condition.

Automatic skew correction leading side to be stepped back toward itsneutral zone a predetermined amount to cause slow down of that end ofthe gate. If such slow down is sufiicient to permit the other end tocatch up and the gate made substantially level, then the slide block ofthe previously leading side is returned to its previous operatingposition. The differential synchro receiver also functions to provideskew correction when the gate is accelerating in the raising or loweringdirection but then the slide block associated with the leading end isstopped in its movement until the other end comes within theaforementioned degree of level therewith and then continues on to itsnormal position for the speed selected. The independent hoisting systemsassociated with the respective gate cnds are thus coordinated tominimize the amount of skew that can occur. A detailed description ofthe control system to afford such operation will now be made.

' 'Let it be assumed that the gate is to be raised at-high LPLSF will betripped.

speed as aforedescribed under Normal-Closing Operation. Under suchconditions the slide block control element zfia will be in its farthest{extreme position in the pumping region and limit switch LPLSD and Ifthe left upper end of the gate leads the right upper end by a smallamount, skew limit switch MDSRSKA closes to complete an energizingcircuit for relay MCRSKA which then closes its contacts MCRSKA- l. Ifsuch lead or skew exceeds a given amount, say one and one-half inches,skew limit switch MDSRSKC then closes to complete an energizing circuitfor relay MCRSKC which is then maintained through closed contactsMCRSKA-4 and MCRSKC-S.

Contacts MCRSKC-l close to complete an energizing circuit for relayLCRSKC through the then closed contacts MLRA-fi, Contacts LCRSKO-Zthereupon close to complete an energizing circuit for contactor LPCOContacts through closed contacts LCRHS-4, LPLSF-2 and interlock contactsLPCC-1. The slide block 26a is then driven back toward its neutral zoneuntil limit switch LPLSF resets to open its contacts LPLSF-Zwhichdeenergizes contactors LPCO to stop movement of the slide block. Thus asthe slide block has been stepped back a small fixed amount toward itsneutral zone, the displacement or output of meter-pump 26 will bedecreased by a corresponding amount to slow down the rate of upwardmovement of the left end of the gate.

Now assuming that slow down of the left end of the gate permits theright end to catch 'up and decrease the skew below one and one-halfinches, limit switch MDSRSKC will reopen. At a point, just prior to theends of the gate coming into exact level, limit switch MDSRSKA reopensto deenergize relay MCRSKA. Contacts MCRSKA-4 of the latter then reopento deenergize relay MCRSKC' and contacts MCRSKC-l reopen to deenergizerelay LCRSKC. Contacts LCRSKC-Z reopen and contacts LCRSKC-l reclose tocomplete an energizing circuit for contactor LPCC through the thenclosed contacts LCRC-Z, LCRHS-3 and LPLSF- 1 and interlock contactsLPCO-l. The slide block is then driven back toward the positionaffording high speed raising of the left end of the gate until limitswitch LPLSF is tripped to open contacts LPSF I to deenergize contactorLPCC which stops the slide block in the position affording high.

speed raising of the left end of the gate.

Now let it be assumed that the gate is being lowered at high speed asaforedescribed under Normal Opening Operation. Under such conditions theslide block control element 26a will be in its extreme position in themetering region. If the left lower end of the gate leads the right lowerend by a small amount, skew limit switch MDSRSKB closes to complete anenergizing circuit for relay MCRSKB and contacts MCRSKB-4 of the latterclose.

If the left lower end of the gate is skewed or leading by an amountinexcess of one and one-half inches over the right lower end, skew limitswitch MDSRSKD closes to complete an energizing circuit for relay MCRSKDwhich is then maintainedv through closed contacts MCRSKB-4 and MCRSKD-S.Closure of contacts MCRSKD-l completes an energizing circuit for relayLCRSKO through the then closed, contacts MLRA-S. Contacts LCRSKO-Z closeto complete an energizing circuit for contactor LPCC through closedcontacts LCRO1-3 and LCRHS-aZ, limit switch contacts LPLSA-1 andinterlock contacts LPCO-1. Thus the slide block will be driven towardits neutral zone a small amount until limit switch LPLSA is reset toopen its contacts LPLSA-1 to deenergize contactor LPCC. Thus as theslide block is stepped back this small amount the metering output of themeter-pump 26 will be decreased'a proportionate amount to slow down therate of downward movement of the left end of the gate.

, If the latst mentioned slow down of the left end of the gate permitsthe right end of the gate to catch up 14 and de'c rease the skew; belowone and one-half inches, limit switch MDSRSKD'will reopen. If the skewdecreases to a point where the left and right ends are sub stantially inlevel, limit switch MDSRSKB will reopen'to deenergi'ze relay MCRSKB andcontacts MCRSKB-4 of the latter then reopen todeenergize relay MCRSKD.MCRSKD-l reopen to deenergize relay- LCRSKO and contacts LCRSKO-Z openand contacts 'LCRSKO-l reclose to complete an energizing circuit'forcontactor LPCO through closed contacts LCRO1-3, LCRHS-l, limit switchcontacts LPLSA-2 and interlock contacts LPCC-1. The slide block is thendriven back toward its extreme position in the metering region and limitswitch LPLSA is tripped to open its contacts which. deenergize contactorLPCO to stop the slide block in the last mentioned extreme positionwherein the left end of the gate is again lowered at high speed.

i The aforementioned skew correction can, of course, take placerepeatedly during closing and opening operations. Skew correction isalso afforded when the gate is accelerating to high speed either duringclosing or opening operation as will now be described.

, Assume that the gate is at rest on the bumpers in fully open positionand that closing operation is initiated-as aforedescribed in connectionwith Normal Closing Operation, that the slide block control elementshave moved from their neutral zone into their pumping region toward highspeed positions. As the gate accelerates upwardly assume that the upperleft end of the gate leads the upper right end an amount sufficient toclose limit switch MDSRSKA, which thereby completes an energizingcircuit for relay MCRSKA to in turn close its contacts MCRSKA-4. If suchlead or skew of the upper left end exceeds one and one-half inches,limit switch MDSRSKC will close to energize relay MCRSKC which thencloses contacts MCRSKO-S to maintain itself. Contacts MCRSKC-l alsoclose to complete an energizing circuit for relay LCRSKC through closedcontacts MLRA-6. As a result contacts LCRSKC-I open to deenergizecontacts LPCC which stop the slide block then attained in the pumpingregion. The meter-pump 26 then pumps at a corresponding rate while meterpump 27 may be assumed to increase its pumping rate to continueaccelerationof the right end of the gate upwardly.

Let it be assumed that the right end catches up and skew is reducedbelow one and one-half inches. Limit switch MDSRSKC will then open. Whenthe skew is reduced to a point where the ends of the gate aresubstantially level, limit switch MDSRSKA opens to deenergizc relayMCRSKA. Contacts MCRSKA-4 open to deenergize relay MCRSKC and opening ofcontacts MCRSKC-l of thelatter results in deenergization ofrelay LCRSKC.Consequently, contacts LCRSKC-l reclose to complete an energizingcircuit for contactor LPCC and thus the slide block 26a is then againdriven toward its extreme position in its pumping region to againaccelerate the left end of the gate upwardly to attain high speeduniform movement of the latter.

Assume that the holding latches have been withdrawn and the slide blocksassociated with meter-pumps 26 and 27 are being driven from theirneutral zones toward their extreme position in the metering region toaccelerate movement of the gate downwardly. Let it be assumed thatduring such movement of the slide blocks the left lower end of the gatebecomes low by a small amount. Limit switch MDSRSKB will then close tocomplete an energizing circuit for relay MCRSKB which then closes itscontacts MCRSKB-4. If such skew increases beyond one and one-half inchesthen limit switch MDSRSKD will close to complete an energizing circuitfor relay 'MCRSKD which is then maintained through closed contactsMCRSKB-4 and MCRSKD-S.

Contacts MCRSKD-l also close to complete an energizing circuit for relayLCRSKO through the closed contacts MLRA-S. Contacts LCRSKO-jl thenope'nt'o deene'rgize contactor IJPCO to stop slide block 26a 'inthe'po'sition then attained and hold the lowering speed of the left endof the gate at the speed then attained while the right end continues toincrease its speed downwardly.

If such corrective action decreases the skew below one and one-halfinches, limit switch MDSRSKD will then open. When the skew is reduced toa point where the ends of the gate are substantially level, limit switchMDSRSKB opens to deenergize relay MCRSKE and the opening of contactsMCRSKE-4 open to deenergize relay MCRSKD and the opening of contactsMCRSKD-l of the latter results in deenergization of relay LCRSKO andreclosure of its contacts LCRSKO-l to again complete the energizingcircuit for contactor LPCO through the closed contacts LCRO1-3, LCRHS-land LPLSA-Z and interlock contacts LPCC-l. Slide block 26a is then againdriven toward its extreme position in its metering region to increasethe speed of the left end of the gate in its downward opening" movement.

The'aforedescribed corrective action takes place within predeterminedlimits of skew, for example one and onehalf inches to three inches. Ifsuch skew correction is not efiective and the skew increases beyond thelarger limit automatic shut down occurs as will hereinafter bedescribed.

Extreme skew shut down If the aforedescribed skew correction is notefiective and the skew continues to increase beyond another limit, forexample three inches, another skew limit switch associated with thesynchro receiver is operated to initiate complete shut down of the gatehoisting system by deenergizing the meter-pump driving motors andsetting of the brake valves. The slide blocks of the meter-pumps arethen driven back to their neutral zones and stopped. A detaileddescription of the system to afford such action follows.

Assume that the gate is being raised, that the automatic skew correctionis unable to decrease or halt the skew or lead of the left upper end andthat such skew ultimately exceeds three inches. Extreme skew limitswitch MDSRSKB will then open to deenergize relay MCRSKE which opens itscontacts MCRSKE-1 to deenergize relay MCRI. Contacts MCRl-l then open todeenergize contactor LPCM which deenergizes motor 34 driving meterpump26, and timing relay LTR. Contacts LTR-1 of timing relay LTR open todeenergize all circuits therebelow which results in setting of the brakevalves. The gate is then stopped and hangs on the cables in thepositions then attained. Relay LC RN is deenergized and recloses itscontacts LCRN-4 to complete an energizing circuit for contactor LPCOthrough the closed contacts MCRI-IL1-2, LCRPD-3 and interlock contactsLPCC-l. Thus the slide block will be driven back toward its neutralzone. As it moves into the neutral zone, limit switch LPLSD is reset toreopen its contacts LPLSD-3 which deenergizes relay LCRPD. ContactsLCRPD-3 of the latter open to deenergize contactor LPCO to stop slideblock 26a in its neutral zone. 7

Let it be assumed that the gate is being lowered and the skew or lead ofthe lower left end exceeds three inches. Extreme skew limit switchMDSRSKB will then open to efiect deenergization of relay MCRl. ContactsMCRl-l then open to eifect deenergization of contactor LPCM and timingrelay LTR to shut down the hydraulic system and hold the gate on thecahlesin the position then attained as aforedescribed. v

Reclosure of contacts LCRN-4 completes an energizing circuit forcontactor LPCC through the then closed contacts MCRHLl-Z, LCRPC-3 andinterlock contacts LPCO-l to afford drive of slide block 26a out of themetering region into the neutral zone. As it passes into the neutralzone limit switch LPLSC is reset to reopen its contacts LPLSC-1 whichdeenergizes relay LCRPC ,to open contacts LCRPC-3 of the latter which 16deenergizes contactor LPCC to stop the slide block26a in the neutralzone.

Manually initiated automatic leveling from extreme skew shutdowncondition 7 Upon restart of drive of the meter-pump and operation of amaster leveling switch the control system will function to return theleading end of the gate into level with the trailing end and stop thehydraulic system to permit initiation of normal closing or openingoperation of the gate as desired. The system takes into account whetherthe gate was being moved in the upward-closing or the downward-openingdirection at the time extreme skew shutdown occurs. Thus, if it occurredon closing then the leading end of the gate is lowered into level withthe trailing end and if it occurred on opening the leading end of thegate is raised into level with the trailing end. A detailed descriptionof the control system operation to afford such action follows:

Let it be assumed that at the time extreme skew shut down occurred thatthe gate was moving upwardly and that the upper left end was leading.Pushbutton switch LPBl is then operated to close its contacts LPBl-Z tocomplete an energizing circuit for relay LCRHLV through stop switch 64,contact LPBl-Z and LCRN-2. Contacts LCRHLV-2 close to complete anenergizing circuit for relay MCRl through the closed limit switchcontacts LGLSA. Contacts MCRl-l then close to complete an energizingcircuit for contactor LPCM and timing relay LTR which are thenmaintained by closure of contacts LPCM-4. Relay LCRHLV is maintainedaround switch LPBI through the then closed contacts LCRHLV-1 and thelatter switch then may be released. At this point the drive motors forthe meter-pump will be energized.

Leveling operation is initiated by operation of hand leveling masterswitch MHLVS to close its contacts MHLVS3- 4 which completes energizingcircuit for relays MCRHLl through their closed contacts LTR-1, LCRHLV3and MCRSKA-3. Relay MCRHLI is then maintained by closure of contactsMCRHLl-l. Contacts MCRHL1-6 close to energize contactor LPCO throughcontacts MCRSKA-l, MLRA-S, LCRPC-1 and interlock contacts LPCC-l. Slideblock 26a is then driven out of its neutr zone into its metering regionand in so doing limit switch LPLSC is tripped to close its contactsLPLSC-1 and LPLSC2.

Closure of contacts LPLSC-1 completes an energizing circuit for relayLCRPC and closure of contacts LPLSC- 2 completes an energizing circuitfor relay LCRBV through their closed contacts MCRHL1-3. Closure ofcontacts LCRBV-1 maintains relay LCRBV around limit switch contactsLPLSC-2 and LPLSD-4 contacts LCRBV-2 and LCRBV-6 close to complete anenergizing circuit for coil LBVl of brake valve LBV to open the latter..Fluid isthen metered out of the upper end of cylinder 9 and the leftside of the gate commences to lower. The last mentioned energization ofrelay LCRPC opens its contacts LCRPC-Lwhich results in deenergization ofcontactors LPCO just as the slide block reaches creeping speed meteringposition. Metering, and consequently lowering, of the left end of thegate, then proceeds at creeping speed until the skew between gate endsdecreases below three inches at which point extreme skew limit switchMDSRSKB recloses to energize relay MCRSKE. Contacts MCRSKE-1 then close.

The left end of the gate continues to be lowered and when the skewdecreases below one and one-half inches limit switch MDSRSKC reopens,and the lowering of the gate continues until the gate ends aresubstantially in level when limit switch MDSRSKA reopens to deenergizerelay MCRSKA. Contacts MCRSKA3 open to deenergize relay MCRHLI.

Contacts MCRHL1-2 reclose to complete an energizing circuit forcontactor LPCC through the closed cont cts LCRN-4, LCRPC-3and interlockcontacts LPCO- 17 1:. Thus slide block 26a is drivenbaclc to the neutralzone and in so doing limit switch LPLSC is reset thereby opening itscontacts LPLSC-1 which eflects deenergization of relay LCRPC. "ContactsLCRPC- 3 open and deenergize contactor LPC-C to stop slide block 26a inthe neutral zone.

Contacts MCRHL1-3 are open concurrently with contacts MCRHLLJ todeenergize relay LCRBV. Contacts LCRBV-Z and 3 then open to deenergizecoil LBVl of brake valve LBV to close the latter. Hence leveling will becompletely halted with the gate hanging on the cables with the oppositeends in level. 7

Similar action is afforded when the gate is being lowered and its leftend is low prior to extreme skew shut down. The system functions thesame up to the point the hand leveling master switch MHLVS is operatedand relay MCRHLl is energized and maintained as aforedescribed. Closureof contacts MCRHLl-6 completes an energizing circuit for contactor LPCCthrough the closed contacts MCRSKBA, MLRA-4, LCRPD-1 and interlockcontacts LPCO-l. Slide block 26a is then driven out of its neutral zoneinto its pumping region, and in so doing limit switch LPLSD is trippedto close its contacts LPLSD-3 and LPLSD-4. Closure of contacts LPLSD-Scompletes an energizing circuit for relay LCRPD and closure of contactLPLSD-4 completes an energizing circuit for relay LCRBV through theclosed contacts MCRHLl-S. Closure of contacts LCRBV-l maintains relayLCRBV around contacts LPLSD-4. Contacts LCRBV-Z and 3 close to completean energizing circuit for LBVI of brake valve LBV to open the latter.Fluid thencommences to be pumped into the upper end of cylinder 9 toraise the left end of the gate. The energization of relay LCRPD effectsopening of contacts LCRPDJ to deenergizecontactor LPCC just as slideblock- 26a reaches minimum speed pumping position. Raising of the leftend of the gate then proceeds at creeping speed until the skew decreasesbelow three inches at which point extreme skew limit switch MDSRSKErecloses to energize relay MCRSKE. Contacts MCRSKE-1 then close.

'The left end of the gate continues to be raised and when the skewdecreases below one and one-half inches, limit switch MDSRSKD reopens,but raising of the left end continues until the gate ends aresubstantially in level. whereupon limit switch MDSRSKB reopens todeenergize relay MCRSKB. Contacts MCRSKB-t open to deenergize relayMCRSKD and contacts MCRSKB-3 open to d-eenergize relay MCRHLI. V I

Contacts MCRHL1-2 recloseto complete an energiz ingcircuit for contactorLPCO through the closed contacts-LCRN4-, LCRPD- 5 and interlock contactsLPCC-1. Thus; slide block 2*6ais driven back to the neutra zone and'inso doing limit switch LPLSD is reset thereby reopening contacts LPLSD -3which eiiects deenergi zati'on of relay LCRPD. Contacts LCRPD-3 open todeenergize contactor LPCO to stop slide block 26a in the neutral zone.

Contacts MCRHLI-S are opened concurrently with contacts MCRHLlt-I todeenergize relay LCRBV which results in closing of brake valve LBV whenthe left end of the gate has been brought back substantially in exactlevel with right end.

Medium, sgecdf operation With the addition ofi' two slide blockposition. limit: switches for each hoisting system, namely, limitswitches: LPLSB and LPLSE for the, left side hoisting system; and RBLSBand RPLSE for the right-hand; hoisting system, as; shown in Fig. 6-,acting in cooperation with, certain. switches and relays; hereafter tobe described in: connection with Figs. 5b and 50, medium. speed: openingand closing: operation of the. gate i'safiordedl Such medium speedoperatiom affords greater gate: lift:-= ing force although. the pumpdriving.- motcrs operate at:

:18 constant speed. speed operation isadvantageous forrai'si'ng the'gate under-extreme load condition,"such as where water may be flowingthereover from the upper pool into the lock for supplemental filling orthe like.

The control to afford medium speed operation additional-ly comprises amanual switch MS, a-relay MCRMS having normally open contacts MCRMS-2and normally closed contacts MCRMS-3, and a relay LCRMS having normallyopen contacts LCRMS1 through LCRMS-4 and normally closed contactsLCRMS-5 and LCRMS-6. With switch MS open, the control system willfunction as aforedescribed in connection with normal closing and openingoperation. Whenswitch' MS is closed relay MCRMS is energized therebyclosing contacts MCRMS-2 and opening contacts MCRMS-3. Accordingly, whenopening and closing switch MOCS' is thereafter closed either to its openor closed contact, relay-LCRMS will thereafterbe energized in place ofrelay LCRHS.

Energization of relay LCRMS results in closure of each of its contactsLCRMS-1 through LCRMS-4 and opening of its contacts LCRMS-5 and LCRMS-6.It will be noted 'that' contact MCRMS-2 is connected in series withrelay LCRMS and together, therewith in parallel with the contactsMCRMS-3 and relay LCRHS. Thus, whenever switch MS is closed toenergizerelay MCRMfi-relat LCRHS will be eliectively excluded from circuit underall operating conditions and relay LCRMS readied for operation in itsstead in exactly the same manner as aforedescribed.

Contacts LCRMS-1 and LPLSB-Z are connected in series and together inparallel with contacts. LCRHS-l and LPLSA-Z thus to render limit switchcontacts LPLB-Z ettective in place of limit switch contacts LPLSA-Z.Similarly, contacts LCRMS-4 and LPLSE-2 are connected in series andtogether in parallel with cont-acts LCRHSF'4 and LPLSF-2 thus to renderlimit switch contacts LPLB-Z effective in place of limit switch contactsLPLSA-Z. Contacts LCRMS-3 and LPLSE-l are connected in series andtogether. in parallel with contacts LCRHS-3 and LPLSF-1i-,. and contactsLCRMS2 and LPLSB-sl are connected inseries and: together in parallelwith contacts LCRHS..2 and LPLSAJ, thus. to render contacts LPLSE-leffective in. place of contacts LPLSF I and to. render contacts: LPLSN-leffective .in' place. of contacts. LPLSA- l- Accordingly, the control:system will function exactly the same upon operation of switch MCOS toits close and open contacts as aforeclescribed under Normal Closing andNormal Opening? operation, except: that the slider block control.element 26bwill beihal'tedi in. intermediate: positions. in: the.pumping and metering region toafford decreased; output of fiuidrfrom'pumpv 26, but at increased output. pressure or back pressure as the casemight be, to raise and lower gate 7 at half speed, but at increasedraising force. or retarded lowering force.

Similarly, the control. system will function the same asaforedescribed'. under: the heading;. Autornatic Skew Correction? exceptthat any corrective action to slow: down orstoptravel of agate end willbe fromihalf; speed rather than-from high speed. i

I claim:

1. In combination, a vertically movable: structure, like hoistingsystems: for each end of the: structure eachcomprising a hydraulicmotor; a variable displacement fluid pump connected: to. said motor andhaving: a control element'operabie in reverse directions froma aneutrait position to effect pumping: of. fluid into or metering it. outof its connected motor and a reversible electric motor: for operatingsaid: control*. element in said reverse directions, and. control meansincluding selectively operable means to. energize said. electric motorsto position said control elements: in a plurality ofcorrespondingpositions: in said reverse directions tosafiordcorresponding pumping and metering rates for said; hydraulic motorsto'raise; and lower said structure.

2. The combination according to'claiml wherein-said selectively operablemeans includes means operable to position said control elements toaiford full and intermediate speed normal pumping and metering ratesselectively at constant pump speeds.

3. The combination according to claim 1 wherein said control meansincludes means operable upon approach of said structure withinpredetermined distances of upper and lower extreme positions to elfectpositioning of said control elements at corresponding positionsaffording reduced raising and lowering speeds of said structure.

4. The combination according to claim 3 together with holding latcheswhich are movable into interfering relation with the structure when thelatter is moved to its upper extreme position, and wherein said controlmeans further includes means responsive to movement of said latches intointerfering relation with said structure to first cause movement of saidcontrol elements to positions corresponding to, but on the opposite sideof their neutral position to that last mentioned to afiord lowering ofthe structure onto the latches and thereafter return said controlelements to their neutral positions and stop operation of said hoistingsystems.

5. The combination according to claim 4 wherein when said structure isin its upper latched position and said control means is operated toselect lowering operation said control elements first move tocorresponding positions affording reduced speed raising of. thestructure to its upper extreme position, and thereafter in response towithdrawal of the latches are moved to corresponding positions on theother side of their neutral positions affording normal speed loweringoperation of said hoisting systems.

6. The combination according to claim 3 wherein said control means alsoincludes means operable upon said structure moving within a givenshorter distance of its extreme positions and the rate of movement ofsaid structure has not been reduced to said lower speed to stop saidhoisting systems and cause return of said control elements to theirneutral positions.

7. The combination according to claim 1 wherein said control meansincludes means responsive to a given difference in level between theends of said structure during raising or lowering of the latter toadjust the control element of one or the other of said pumps apredetermined amount to change the rate of movement of one end of thestructure with respect to the other.

. 8. The combination according to claim 7 wherein said means responsiveto a given difference in level between the ends of said structureresponds to adjust the control element of the pump of the hoistingsystem connected to the leading end of the structure said predeterminedamount to slow down the leading end of the structure.

9. The combination according to claim 8 wherein the last specified meansis also responsive to decrease in difference in level between the endsof said structure below said given dilference to readjust the controlelement of the pump of the hoisting system of the leading end of thestructure back to its normal position for the selected direction ofmovement of the structure.

10. The combination according to claim 7 wherein the last recited meanswhen said given difference in level occurs and either of said controlelements are being moved toward any of said predetermined positionsstops the movement of one or the other of said control elements untilthe ends of the structure are substantially in level.

11. The combination according to claim 7 wherein said control meansfurther include means responsive to another greater diiference in levelof the ends of the structure during raising or lowering to stopadmission of fluid into or exhaustion of the same from said pistonmotors to stop and hold the structure in the position then attained. a a

l2.-The combination according to claim'll wherein said selectivelyoperable means includes means operable following the last mentionedstopping of said structure to operate'one or the other of said motorsindividually to operate its control element to one or the other of saidpredetermined positions on opposite sides of its neutral position toraise or lower the connected end of said structure until brought intolevel with the other end thereof.

13. The combination with a vertically movable gate for a navigation lockor the like, of like hoisting systems for each end of the gate, each ofwhich comprises a hydraulic piston motor, an electrically drivenvariable displacement fluid pump connected to said motor and having acontrol element operable in reverse directions from a neutral positionto alford pumping of fluid into said motor to cause said piston to raiseits connected gate end and to meter said fluid from said motor to permitsaid gate end to lower under its own weight, an electroresponsive valvein the fluid circuit between said pump and said piston motor which isenergizable to open said fluid circuit, and a reversible electric motorfor operating said control element in said reverse directions, andelectrical control means including switches selectively operable toenergize said valves and said electric motors to position said controlelements in a plurality of corre' sponding positions to affordcorresponding pumping and metering rates for said piston motors forraising and lowering said gate.

14. The combination according to claim 13 together withelectroresponsive brakes for each of the aforementioned electric motorswhich are energizable and deenergizable concurrently with theirrespective motors to release and set the motor shafts.

15. The combination according to claim 13 wherein said control meansincludes a plurality of limit switches and differential synchro controlmeans for said switches to operate certain of the latter upon occurrenceof a given difference in level between the ends of said gate duringraising or lowering to effect adjustment of the control element of oneor the other of said pumps a predetermined amount to correspondinglychange the rate of movement of one end of the gate with respect to theother.

16. The combination according to claim 15 wherein operation of saidcertain of said limit switches causes the control element of the pump ofthe hoisting system connected to the leading end of the gate to be movedback toward its neutral position a predetermined amount to slow down therate of movement of the leading end of the gate, and wherein the lastmentioned limit switches thereafter respond upon decrease in differencein level belowsaid given amount to reposition such control element backto its normal position for the selected direction of gate travel.

. 17. The combination according to claim 15 wherein operation of saidcertain of said limit switches when either of said control elements isbeing moved toward a predetermined position stops movement of one or theother of said control elements until such limit switches reset upon theends of the gate being returned to substantially in-level condition.

18. The combination according to claim 15 wherein upon occurrence ofanother greater difference in level between the gate ends other of saidlimit switches operate to deenergize said valves and the pump drivingmotors and return the control elements to their neutral positions tostop movement of said gate.

19. The combination according to claim 18 wherein said control meansincludes an electric switch which when operated following the lastmentioned stopping initiates operation of the control system to operateone or the other of the control element driving motors individually toone or the other of predetermined positions on opposite sides ofjtsneutral position and energize the 21 22 associated one of said valves toraise or lower the associ- 2,353,389 Cannon July 11, 1944 ated end ofsaid gate until brought substantially in level 2,367,580 Hines Jan. 16,1945 with the other end thereof. 2,400,685 Collins May 21, 19462,526,252 Mercier Oct. 17, 1950 References Cited in the file of thispatent 5 2,603,145 Dreis July 15, 1952 UNITED STATES PATENTS FOREIGNPATENTS 2,192,510 Smith Mar. 5, 1940 544,417 Canada Aug. 6, 19572,353,388 Cannon July 11, 1944

